title: Pharmacological characterization of YM087, a potent, nonpeptide human vasopressin V1A and V2 receptor antagonist.
abstract: The effects of YM087 (4'-[(2-methyl-1,4,5,6-tetrahydroimidazo[4,5-d] [1]benzazepin-6-yl)-carbonyl]-2-phenylbenzanilide monohydrochloride), a novel nonpeptide vasopressin (AVP) receptor antagonist, on [3H]AVP binding to human AVP receptors (V1A, V1B and V2) cloned and transiently expressed in COS-1 cells generated from monkey renal tissue were studied. Scatchard analysis of saturation isotherms for the specific binding of [3H]AVP to membranes, prepared from COS-1 cells transfected with human V1A, V1B and V2 receptors, yielded an apparent equilibrium dissociation constant (Kd) of 0.67 nM, 0.28 nM and 2.14 nM and a maximum receptor density (Bmax) of 2180 fmol/mg protein, 369 fmol/mg protein and 2660 fmol/mg protein, respectively. YM087 showed high affinity for AVP V1A and V2 receptors with Ki values of 6.3 and 1.1 nM, respectively, but had no effect on [3H]AVP binding to AVP V1B receptors. In COS-1 cells expressing either AVP V1A or V1B receptors, AVP caused a concentration-dependent increase in intracellular Ca2+ concentration ([Ca2+]i). YM087 inhibited the AVP-induced increase in [Ca2+]i in COS-1 cells expressing AVP V1A receptors in a concentration-dependent manner with an IC50 value of 14.3 nM, but did not influence this increase in AVP V1B-receptor expressing cells. In contrast, stimulation of COS-1 cells expressing AVP V2 receptors resulted in an accumulation of cAMP. YM087 inhibited AVP-induced cAMP production in COS-1 cells expressing AVP V2 receptors in a concentration-dependent manner with an IC50 value of 1.95 nM. In all assays used, YM087 was devoid of any agonistic activity. These results suggest that YM087 is a potent nonpeptide dual human AVP V1A and V2 receptor antagonist, and that YM087 will be a powerful tool in investigation of the physiological and pathophysiological roles of AVP.
authors.affiliation: Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., Tsukuba, Ibaraki, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Tahara
authors.forename: M
authors.initials: M
authors.lastname: Saito
authors.forename: T
authors.initials: T
authors.lastname: Sugimoto
authors.forename: Y
authors.initials: Y
authors.lastname: Tomura
authors.forename: K
authors.initials: K
authors.lastname: Wada
authors.forename: T
authors.initials: T
authors.lastname: Kusayama
authors.forename: J
authors.initials: J
authors.lastname: Tsukada
authors.forename: N
authors.initials: N
authors.lastname: Ishii
authors.forename: T
authors.initials: T
authors.lastname: Yatsu
authors.forename: W
authors.initials: W
authors.lastname: Uchida
authors.forename: A
authors.initials: A
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000494:pharmacology*; D001552:Benzazepines / Q000494:pharmacology*; D001667:Binding, Competitive; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006490:Hemostatics / Q000494:pharmacology; D006801:Humans; D011869:Radioligand Assay; D017483:Receptors, Vasopressin / Q000235:genetics / Q000378:metabolism; D012044:Regression Analysis; D012076:Renal Agents / Q000494:pharmacology; D014162:Transfection
chemical_list: D065092:Antidiuretic Hormone Receptor Antagonists; D001552:Benzazepines; D006490:Hemostatics; D017483:Receptors, Vasopressin; D012076:Renal Agents; C106389:conivaptan; D001127:Arginine Vasopressin; D000242:Cyclic AMP; D002118:Calcium